• There has been a recent cluster of spammers accessing BARFer accounts and posting spam. To safeguard your account, please consider changing your password. It would be even better to take the additional step of enabling 2 Factor Authentication (2FA) on your BARF account. Read more here.

Backfiring during engine braking

EastBayDave said:
Listen to the man; he KNOWS from experience!

Every time I've put an aftermarket (full) system on (never tried a slip-on), they are always slightly lean off idle, which causes backfires on decel. Richen it up on the idle circuit a little & see what happens. May only be a few turns of the idle screw...

If your lucky, done. :teeth :ride
Click to expand...

when you say "turn out" do you mean adjust my idle screw to increase or decrease the idle? also is this the screw that is on the left side of the bike to adjust up or down the idle speed?
 
Last edited:
afm199 said:
If you want to get technical, replace the stock SV pilot jets (115) with 117.5 or just turn the fuel screws out a half turn. But before you do that answer how many plates you are running on the SV, what airfllter and what mains. If you don't know that, then just throw money at it, sooner or later some of the dollar bills will partially clog up the airbox snorkel, richen the mixture and fix the problem.

however you probably have an air leak.
Click to expand...

i am running 5 plates right now, not sure about the airbox or mains as i just got the bike but i'm pretty sure they are stock. will turning the fuel screws help in this situation? :teeth
 
djgtekfrmsanjo said:
when you say "turn out" do you mean adjust my idle screw to increase or decrease the idle?
Click to expand...

Back to square one. You don't have a clue here. Until you do the work you won't ..

Pull the carbs, check main jet size, see if there are stock needles, and check pilot jet size. The idle circuit is not the idle screw. It is completely different. Actually is the pilot circuit/fuel screws.
 
djgtekfrmsanjo said:
i am running 5 plates right now, not sure about the airbox or mains as i just got the bike but i'm pretty sure they are stock. will turning the fuel screws help in this situation? :teeth
Click to expand...

Five plates is not that lean. If you turn out the fuel screws a half turn it should help.

IF mains are stock, pilot jets are stock, needles are stock, and you have no air leaks.
 
Don't fix it if it isn't broken.

If you have an exhaust leak, or a mixture problem, fix it. Especially with carbs, it makes sense to dyno the engine for $50, just to make sure that you aren't overheating your valves with lean fueling.

But if the PAIR system causes the exhaust to pop by design and it isn't harming anything, don't worry about it.
 
is there anyone in the fremont/santa clara area that anyone can recommend to take a look at my bike at a decent price? honestly, i'm not experienced enough to start pulling carbs out of my bike...
 
djgtekfrmsanjo said:
is there anyone in the fremont/santa clara area that anyone can recommend to take a look at my bike at a decent price? honestly, i'm not experienced enough to start pulling carbs out of my bike...
Click to expand...

define decent.
 
afm199 said:
define decent.
Click to expand...

when taking into account all shops/individuals that do this type of work in the area, that they don't fall into the top 75% in cost :thumbup

or honestly, cost aside, recommend someone who can do the job right and efficiently for me...
 
Last edited:
djgtekfrmsanjo said:
when taking into account all shops/individuals that do this type of work in the area, that they don't fall into the top 75% in cost :thumbup

or honestly, cost aside, recommend someone who can do the job right and efficiently for me...
Click to expand...

I can pull your carbs and do a rebuild if that's what you need. Actual tuning beyond the basics are a little out of my league - It takes a long time and a lot of work to tune the carbs by feel/plug condition - generally, it's more efficient to take it to a dyno shop, where a typical carb tune will cost around $300.
 
Lesbusa said:
Winna! Check for the condition of your emissions system.
Click to expand...

Yep. Had a malfunctioning system on my ST once and it was allowing too much air into the intake system on deaccelleraton. Sounded cool but eventually the problem got so bad I couldn't start the bike. Removed the system and all was good again.
 
jc2ducati said:
Ive got this condition on my bike too. Its got aftermarket pipes. With both dbkillers in, i dont notice it, however, i now have only 1 in, and get those pops on decel only.

What about the lean mixture would cause those pops? Im missing something. Is it basically detonation? I thought detonation was associated with pinging and not exhaust popping?
Click to expand...

Detonation is internal, inside the combustion chamber. Yes, it's the same thing as pinging.
 
Brown81 said:
Anyone? Bueller? Elskip???


(someone once told me it could be exhaust manifold gasket leak?)

:cool
Click to expand...


Sometimes if you just crack the throttle open just a bit, it lets just enough air in to start the popping. I can sometimes do that on my Mini. It pops and burbles a lot on deaccelleration and then stops, but if I feed in just a hair or throttle, enough air is let in to start the popping again.
 
djgtekfrmsanjo said:
or honestly, cost aside, recommend someone who can do the job right and efficiently for me...
Click to expand...
myself & a few others in this thread could fix it for you, as could a couple other folks on the board. just do a search for mechanics.
 
djgtekfrmsanjo said:
when taking into account all shops/individuals that do this type of work in the area, that they don't fall into the top 75% in cost :thumbup

or honestly, cost aside, recommend someone who can do the job right and efficiently for me...
Click to expand...


You don't want decent.. you want it done right. 'Decent' is a rattle can paint job.

Rob @ Evolution in San Jose.. he's one of the sharpest mechanics I know.

AFM199. Can't go wrong..

Or Elskippo... He's the forums resident motorcycle repair subject-matter-expert. He gets rave reviews from like, everyone.

I don't enjoy working on twins unless it's a oil spewing, air leakin, potato farting Harley.
 
Burning1 said:
Don't fix it if it isn't broken.

If you have an exhaust leak, or a mixture problem, fix it. Especially with carbs, it makes sense to dyno the engine for $50, just to make sure that you aren't overheating your valves with lean fueling.

But if the PAIR system causes the exhaust to pop by design and it isn't harming anything, don't worry about it.
Click to expand...

To a point. But, for instance, if the PAIR system continues to disintegrate, it can cause problems. But then that will be fairly obvious. PAIR systems often have a vacuum operated air pump. Engine vacuum acts on a spring loaded diaphram which then pumps the air into the exhaust port. If the pump diaphrams develop holes or cracks, extra air can get sucked into the engine the wouldn't otherwise. This can cause lean running or even make it very difficult to start. If everything is OK now, then it should be fine to leave as is. But, should the bike become hard to start or have other difficulties when running, then I'd take another look at the PAIR system.
 
ST Guy said:
Sometimes if you just crack the throttle open just a bit, it lets just enough air in to start the popping. I can sometimes do that on my Mini. It pops and burbles a lot on deaccelleration and then stops, but if I feed in just a hair or throttle, enough air is let in to start the popping again.
Click to expand...

This isn't popping or burbling. This one really loud BANG. It doesn't pop or burble at all on decell. Only after I reapply throttle and its just one loud bang.


Sorry for the threadjack OP!
 
You must log in or register to reply here.
Back
Top